[Emacs-diffs] master 66839a7 2/2: * src/fns.c (Flocale_info): Avoid fixnum overflow under ASan.

[Philipp Stephani]

branch: master
commit 66839a74bb74efa16f9f531e93d58cadf6ab7196
Author: Philipp Stephani <address@hidden>
Commit: Philipp Stephani <address@hidden>

    * src/fns.c (Flocale_info): Avoid fixnum overflow under ASan.
---
 src/fns.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/fns.c b/src/fns.c
index fa52e5e..37c581f 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -3176,8 +3176,14 @@ The data read from the system are decoded using 
`locale-coding-system'.  */)
 # endif
 # ifdef HAVE_LANGINFO__NL_PAPER_WIDTH
   if (EQ (item, Qpaper))
-    return list2i ((intptr_t) nl_langinfo (_NL_PAPER_WIDTH),
-                  (intptr_t) nl_langinfo (_NL_PAPER_HEIGHT));
+    /* We have to cast twice here: first to a correctly-sized integer,
+       then to int, because that's what nl_langinfo is documented to
+       return for _NO_PAPER_{WIDTH,HEIGHT}.  The first cast doesn't
+       suffice because it could overflow an Emacs fixnum.  This can
+       happen when running under ASan, which fills allocated but
+       uninitialized memory with 0xBE bytes.  */
+    return list2i ((int) (intptr_t) nl_langinfo (_NL_PAPER_WIDTH),
+                  (int) (intptr_t) nl_langinfo (_NL_PAPER_HEIGHT));
 # endif
 #endif /* HAVE_LANGINFO_CODESET*/
   return Qnil;